AUTOMATIC SELF-PROPELLING APPARATUS FOR OVERHANGING CONTACT LINES

Abstract: Subject-matter of this invention is an automatic self-propelling apparatus for overhanging contact lines comprising one or two messenger cables (28, 29; 32) and two conductor wires (30, 31) and consisting of two symmetrical sections, which are operable in both movement directions and are arranged upon a railway truck provided with two drive and control cabs, said sections being mounted upon a platform (13) vertically movable by means of an articulated parallelogram structure (shears) (14), each above mentioned section including, as essential component parts: a device (27) for receiving the conductor wires (30, 31) and for detecting any twist thereof around the longitudinal axis; a lower spreading apart and clamping assembly to spread apart and to lock in certain positions the conductor wires (30, 31) as they emerge from the twist detecting device (27); an upper spreading apart and clamping assembly (25) to receive from the external supply, to spread apart and to lock in certain positions the above quoted messenger cables (28, 29); two power operated magazines (16, 18; 17, 19) containing the necessary sets of hangers to be used in an overhanging cycle; a cylindrical/cartesian robot (20, 21) having five degrees of freedom and provided with a beam bearing a telescopic cross-arm (22) with devices mounted at its end for picking up, positioning and fastening the hangers, said robot being adapted to pick up the hangers from said magazines (16, 18; 17, 19) and to install them between said messenger cables (28, 29; 32) and said conductor wires (30, 31), as well as a computer based system to cause the railway truck to move forwardly at a rigorously constant speed and the robot to move rearwardly at the same speed, so that a null relative speed exists between the robots and the line, and to control all other steps related to powering the magazines, picking up the hangers from the magazines and installing them.

Description: AUTOMATIC SELF-PROPELLING APPARATUS FOR OVERHANGING CONTACT LINES This invention broadly relates to the general field of manufacturing and maintaining contact lines for railway electric traction and, more specifically, in the frame of a specialized yard for performing such works, it concerns an automatic self-propelling apparatus to carry out the overhanging work of such lines. As it is known, the contact lines for railway electric traction comprise one or two bearing cables, generally designated as "messenger cables", on which conductor wires are hanged, generally designated as "contact wires", by means of connection, wire-shaped devices, generally designated as "hangers". The pantograph trolley of the train slides in contact with said contact wires and absorbs therefrom the electric current to supply the traction motors thereof. As further preliminary information, it can be stated that the messenger cables are usually made of copper, but they can also be made of any other material, possibly having a higher mechanical strength, in particular when they are not requested to supply electric current and when they play mainly a support role. As it is easy to understand, in operation they have a catenary shaped geometrical profile. The contact wires are conventionally made of copper and have a so designated "shaped" cross-section; the "shape" of the contact wires is a noticeable feature of this invention, as it will appear hereinafter. The contact wire should be extended in horizontal trim with very small tolerances, in order to guarantee a continuous and uniform contact with the pantograph trolley. Due to the fact that the messenger cables and the contact wires extend along different paths, the hangers to be used along the line have different lengths and consequently a hanger having a well defined length corresponds to each position along the line. The specialized application field for the apparatus according to this invention, therefore, is interested in installing the hangers to be used to connect the contact wires to their support cables, respectively. It is considered as useful for the comprehension of this description to furnish some information upon the technical state of the art, in order to better disclose the improvements proposed by this invention. The line trunk to be worked at has usually a length of about 1200 m to 1400 m. When the work to be done is a maintenance work to substitute an already worn section of the line, such work is to be carried out during dwells in the railway traffic, namely intervals usually having a duration of about 2.5 to 3 hours. The contact line to be extended or "stretched" is to be completed and made operative during this time interval such that, upon termination of the railway traffic dwell, the train should be enabled to run through the repaired trunk at full nominal speed and without restrictions of any kind. At the present state of the art, the hanger installing step, so- called "hangering" step, is very expensive because it requires a noticeable resource employment, both from the equipment and from the workmen view point. At present, in particular, when the above indicated times and lengths are to be fulfilled, as an average evaluation, about 10 to 14 workmen and 5 to 7 self-powered railway trucks (power ladders) are to be employed to carry out the hanger installation step along the concerned railway trunk. As a matter of facts, respective sections of the trunk to be equipped are assigned to the above stated workmen, divided into groups comprising two or three workmen for each power ladder, and the hanger installing work is exclusively carried out by manual means. Besides being extremely delicate due to the above mentioned strict tolerance limits to be respected, the work to be done is also very heavy, in view of the fact that the number of hangers to be installed along an average section of the contact line trunk is about 400 units. The apparatus according to this invention provides for carrying out in a completely automatic manner all hanger installation steps, with a working rate perfectly compatible with the comprehensive working requirements connected with extending or "stretching" a contact line. A self-propelling apparatus according to this invention works in association with and under control of a computer, operating under instructions deriving from a dedicated computer program, both of which are not part of this invention, such that, for the apparatus to be operative, it is only necessary that it be supplied in the workshop with all hangers needed for installation along the predetermined section of the line to be equipped and that it be brought to a useful position adapted for starting the desired work, that otherwise would require a high number of manual workmen and related power ladder. From a self moving capability view point, the apparatus is mounted upon a self propelling railway truck, adapted to autonomously move along a railway track made according to conventional railway specifications. Specific subject-matter of this invention therefore, is an automatic self-propelling apparatus for overhanging contact lines comprising one or two messenger cables and two conductor wires and consisting of two symmetrical sections, which are operable in both movement directions and are arranged upon a railway car provided with two drive and control cabs, said sections being mounted upon a platform vertically movable by means of an articulated parallelogram structure (shears), each above mentioned section including, as essential component parts: - a device for receiving the conductor wires and for detecting and correcting any twist thereof around the longitudinal axis; - a lower spreading apart and clamping assembly to spread apart and to lock in certain positions the conductor wires as they emerge from the twist detecting device; - an upper spreading apart and trapping assembly to receive from the external supply, to spread apart and to lock in certain positions the above quoted messenger cables; - two power operated magazines containing the necessary sets of hangers to be used in an overhanging cycle; - a cylindrical/cartesian robot having five degrees of freedom and provided with a beam bearing a telescopic cross-arm with devices mounted at its end for picking up, positioning and securing the hangers, said robot being adapted to pick up the hangers from said magazines and to install them between said messenger cables and said conductor wires, as well as - a computer based system to cause the truck to move forwardly at a rigorously constant speed and the robot to move rearwardly at the same speed, so that a null relative speed exists between the robots and the line, and to control all other steps related to powering the magazines, picking up the hangers from the magazines and installing them. Further details and advantages of this invention will be evident from the following specification by referring to the enclosed drawings wherein the preferred embodiment is shown by way of illustration and not by way of limitation. In the drawings: Figure 1 is an elevation side view of an apparatus according to this invention, mounted upon a railway truck; Figure 2 is an plan view of the apparatus of Figure 1 ; Figure 3 is an elevation side view of the apparatus of this invention, corresponding to Figure 1, but with the hanger magazines removed, in order to make the rearwardly arranged components visible; Figure 4 is a cross-section view taken along line A-A of Figure Figure 5 is a cross-section view taken along line B-B of Figure 3; Figure 6 is a partial front elevation view showing the arrangement of the apparatus at its upper working level, in the case of two messenger cables and two contact wires; Figure 7 is a partial front elevation view showing the arrangement of the apparatus at its upper working level, in the case of a single messenger cable and two contact wires. By referring now to the drawings and particularly to Figures 1 , 2 and 3, it can be observed that the apparatus according to this invention comprises two symmetrical sections and, since it should be capable to indifferently work in both movement directions, it is mounted upon a railway truck or car 10 provided with two drive and control cabs 11 , 12. The apparatus in its whole is arranged upon a platform 13 vertically movable by means of an articulated parallelogram structure (shears) 14, so as to guarantee that it remain always parallel to the ground plane. Platform 13 is made as a trestle carpentry work, sufficiently rigid to limit any static or dynamic deformations caused by fixed and movable components of the system to very low values. The necessary hangers 15 are housed in four magazines 16, 17, 18, 19, each of which, as a matter of facts, is formed by two pulleys or toothed wheels around which a belt or chain is extended having the concerned hangers removably suspended therefrom. Further details of said magazines 16 to 19 are not furnished here because such structural particulars can be easily conceived by any person skilled in the art and a number of variations can be made only provided that the functions they have to perform are understood. To this purpose, it is important to explain that the positions the individual hangers have to take within the magazines are strategically 5 arranged, in view of the fact that a biunivocal correspondence exists between each individual point along the line and the hanger which in that position is to be employed to hang the contact wire on the overhanging catenary-shaped messenger cable. The hangers are arranged, therefore, according to a logic and strictly defined succession, so as to be 10 successively picked up and installed. The installation of the hangers per se is carried out by means of a suitable automatic mechanical apparatus (robot) which will be broadly described herein below and some structural particulars of which are subject-matter of a separate patent application. 15 Magazines 16 to 19 are individually powered, for instance by means of asynchronous motor-reducer assemblies driven by inverters and equipped with encoders, connected to a central common control computer system acting under instruction deriving from a suitable software, both of which are not part of this invention. The control system, anyway, should 2.0 be capable to detect the individual positions and to control the movements of the individual magazines, as well as the movements of any other component of the apparatus, with millimetric accuracy, in view of the extremely strict allowable tolerances. Even if such work can be made by manually operating 25 workmen, as above mentioned, two robots 20, 21 are mounted upon said platform 13, such robots being the most suitable apparatus to automatically perform the picking up operations of the hangers 15 from their respective magazines 16 to 19 and their installation between the messenger cables and the contact wire. The robots are equipped with 30 prehensile members comprising telescopic, bidirectionally symmetrically extendible cross-arms 22, driven for instance by means of a motor- reducer assembly, conveniently by means of a screw/nut-screw pair with right-hand/left-hand thread. Cross-arm 22 is mounted at the end of a beam portion of the robot by means of a centrally located, circonferential 35 clamping device (not shown). The robots have five degrees of freedom (three translation movements, a rotation movement around its vertical axis, an angular movement of its head bearing the cross-arm 22). In addition to this degrees of freedom of the robot, a further degree of freedom can be added, strictly connected to the above described cross- arm per se, namely its telescopic extension movement. Of course, cross-arm 22 has geometrically variable overall dimensions so as to exhibit reduced dimensions during installation operations involving short hangers, in order that the overall external dimensions of the whole apparatus be smaller than the rolling stock clearance gauge. To this effect, for instance, a motor-reducer assembly of asynchronous type with control inverter and associated open ring encoder of well known kind can be adopted. From a structural point of view, the above explained cross-arms 22 have prehensile, pneumatically operated devices (not shown) mounted at their ends, adapted to pick up with accurate precision the hangers from the magazines. Furthermore, each cross-arm 22 has, fixedly mounted at its ends, two pneumatically operated screwers designed to be used after having inserted the clamps of the hangers, for locking the fastening bolts of the hangers themselves, as those skilled in the art will easily understand. As important components of the cross-arms, sensors are provided to detect and check the relative positions between the conductor or contact wire and its supporting messenger cable, in order to millimetrically control the position of the attachment points of the hangers, as well as the positions of clamping devices equipped with rolling members which grasp both the conductor or contact wire and the messenger cable and, upon terminating the installation operation of a hanger, open themselves to start the installation cycle of the subsequent hanger. Spreader assemblies comprising rollers or pulleys 23 are provided on platform 13 at the working ends of robots 20, 21. Since the conductor wires or the messenger cables are dispensed from an external supply not included in the apparatus of the present invention and since they are dispensed generally in coupled form and anyway in uncertain position, the main role of said spreader assemblies is, in the first place, to spread apart the concerned wires (conductor wire and messenger cable), thereby preventing them from folding and, in the second place, by co¬ operating with lower and upper clamping assemblies arranged downwardly therefrom, to bring the contact wires and the messenger cables to stable and certain positions. The above set forth lower and upper clamping assemblies 24, 25 comprise at least two pulley pairs which grasp the wire or the cable in order to clamp them in stable and certain position, so as to prevent them from displacing with respect to the laying axis, in preparation to installing the respective hangers in the desired positions. During work, the so hanged and clamped contact wire is of course stretched along its axis. The stretching level cannot be higher than a pre-established limit value, but it should anyway be such that the unavoidable camber is reduced to a so low value, for instance only two or three millimetres, as to be amenable to be subsequently eliminated by movable clamping members mounted on the cross-arms 22 of robots 20, 21. It should be noted that the lower and upper clamping assemblies 24 and 25, at both sides of platform 13, should be adapted to be opened in order to enable the clamps of the hangers to pass there through. In fact, should it be not so, since such clamps have overall dimensions greater than the dimensions of the wire or cable, they could not pass through the race of the pulleys. Opening of the grasping assemblies is effectively made possible by manufacturing the pulleys as two separable or spreadable apart half pulleys. To this purpose, it is to be specified that, as above mentioned, each lower and upper clamping assembly should comprise at least two pulley pairs in order that, when the pulleys of a first pair are spread apart to enable the clamp of a hanger to pass there through, the pulleys of the second part are kept closed in order to anyway maintain the wire in stable position along the laying axis. In this operation way, the pulley pairs are alternatively opened and closed in the installation movement direction during the passage of each hanger. Since the messenger cables are not extended in straight horizontal line, but they follow a catenary shaped curve, the upper clamping assemblies, differently with respect to the lower ones, are mounted upon hydraulically vertically movable platforms 26, operated by the already mentioned central common computer control system, for instance, by means of analogue potentiometers which are incorporated with the drive assembly and furnish feedback signals corresponding to the real height position of the cable. As a matter of facts, upon comparing the real vertical position of the hanger to the nominal position thereof, platforms 26 are moved oleodinamically or with any other operation mechanism in order to bring the difference to zero value. In this manner, the system in effect divides the catenary shaped geometrical profile of the messenger cables into a stepped broken line, wherein each step corresponds to a single hanger section of the line. A further important component of the apparatus according to this invention is a device designed to detect a twisted condition in the contact wire. Since, in contrast to the messenger cables, the contact wires are specifically shaped in order to optimise the contact with the pantograph trolley, it is apparent that twists of the contact wires greater than a maximum tolerance circuit are not permissible. Aiming at detecting the twists of the contact wires with respect to their longitudinal axis, two twist detection and possibly correction devices 27 are provided at both inlet sides of the apparatus, for operation in both movement directions, namely at both ends of the platform, that is to say immediately before or upstream of the hanger installing point. Said twist detecting devices 27 comprise shaped pulleys the outline of which inversely duplicates the shape of the contact wire and they are mounted upon base structures adapted to rotate around their own longitudinal axis when transversal twists are present in the wire with values higher than the preload of return springs. Said preloaded condition of the springs is per se capable to correct small twists of the contact wire. When the limit value is overcome, -the resulting condition will be considered from any view point as an error condition and, as such, it will result into stopping the operation of the apparatus and requiring the intervention of a workman to manually correct the error. OPERATION The railway truck equipped as above explained will be moved by an autonomous propulsion assembly which causes it to run along the railway track at a rigorously constant velocity strictly matched to the longitudinal velocity of the robots mounted thereupon. The longitudinal positions of the hangers can be derived from the well known hanger installation tables preliminariy included in the memory of the management computer, so that a determined hanger will be associated with each hanger installation position. The hanger installation operation will be carried out while the railway truck is moving and while also the robots are moving, but in opposite direction with respect to the truck, the movements of the truck and of the robots are rigorously performed at the same velocity, so that the truck and the robots have a relative velocity rigorously null, or in other words the are perfectly stationary with respect to the messenger cable/contact wire system. The robot, upon completing the installation operation of a hanger, will immediately return to a central position on the platform, in order to be supplied with a new hanger or, more precisely, with the subsequent hanger, which is uniquely determined. Such a hanger, in fact, is the one already present in strategic position, because it is located and moved in "shadow" time by the computer system. The start of the so-called span count is determined by an optical sensor which will locate a suitable position 0 corresponding to time 0, wherefrom ail movements of the system will be started, under clock control deriving from the hanger installation tables already preliminariy stored therein. The operation by which a hanger 15 is inserted between the conductor wire and the associated messenger cable is made possible by exploiting the five degrees of freedom of the robot plus the additional degree of freedom connected with the cross arm. Screwing of the hanger clamps is effected by means of pneumatic screwers suitably oriented and mounted at the ends of the cross arm. Upon tightening the clamps, the robots withdraw their beams and, afte having opened the movable clamping assemblies arranged on the cross-arms, they quickly return back to the pick up position for picking up the subsequent hanger. The robots operate one in front of the other and each of them operates upon one hanger of each hanger pair, respectively. The two robots are independent on one another and, therefore, it is possible to work with one only robot of a pair, should one of them be inoperative. In this case, the hangers that are not installed by an inoperative robot should be installed by the conventional manual procedure. The condition of the apparatus operating at its working level along a line comprising two messenger cables 28 and 29 with two conductor wires 30 and 31 is shown in Figure 6, wherein robot 20 is illustrated during the installation of a hanger, while robot 21 is illustrated during the picking up operation of a subsequent hanger from the associated magazine. Figure 7 shows a working condition of the apparatus at its upper level along a line comprising a single messenger cable 32 and two conductor wires 30, 31. In this case, it should be remarked that the cross-arm 22 is tilted in order to accommodate the angular deviation between messenger cable 22 hangers 30 and 31, alternatively arranged at either side thereof.

Claims: CLAIMS 1. An automatic self-propelling apparatus for overhanging contact lines comprising one or two messenger cables (28, 29; 32) and two conductor wires (30, 31 ), characterized in that it consists of two symmetrical sections, which are operable in both movement directions and are arranged upon a railway car provided with two drive and control cabs, said sections being mounted upon a platform (13) vertically movable by means of an articulated parallelogram structure (shears) (14), each above mentioned section including, as essential component parts: - a device (27) for receiving the conductor wires (30, 31 ) and for detecting any twist thereof around the longitudinal axis; - a lower spreading apart and clamping assembly to spread apart and to lock in certain position the conductor wires (30, 31 ) as they emerge from the twist detecting device (27); - an upper spreading apart and clamping assembly (25) to receive from the external supply, to spread apart and to lock in certain position the above quoted messenger cables (28, 29); - two power operated magazines (16, 18; 17, 19) containing the necessary sets of hangers to be used in an overhanging cycle; - a cylindrical/cartesian robot (20, 21) having five degrees of freedom and provided with a beam bearing a telescopic cross-arm (22) with devices mounted at its end for picking up, positioning and securing the hangers, said robot being adapted to pick up the hangers from said magazines (16, 18; 17, 19) and to install them between said messenger cables (28, 29; 32) and said conductor wires (30, 31), as well as - a computer based system to cause the railway truck to move forwardly at a rigorously constant speed and the robot to move rearwardly at the same speed, so that a null relative speed exists between the robots and the line, and to control all other steps related to powering the magazines, picking up the hangers from the magazines and installing them. 2. A self-propelling automatic apparatus for overhanging contact lines according to claim 1 , characterized in that said device (27) for detecting any twist in said conductor wires (30, 31 ) comprise shaped pulleys the outline of which inversely duplicates the shape of the contact wire and they are mounted upon base structures adapted to rotate upon their longitudinal axis when a transversal twist is present in the wire, in contrast with the force of preloaded return springs. 3. A self-propelling automatic apparatus for overhanging contact lines according to claim 2, characterized in that the preload grade of said return springs is sufficient to correct any small twists of the contact wire. 4. A self-propelling automatic apparatus for overhanging contact lines according to claim 2, characterized in that the rotation of the base structures bearing said pulleys is defined by two limit positions that establish the maximum tolerance levels of the contact wire twists beyond which the apparatus provides for stopping the operation and for commanding the corrective manual intervention of a workman. 5. A self-propelling automatic apparatus for overhanging contact lines according to claim 1, characterized in that said lower spreading apart and clamping assembly (23) comprises a set of horizontal axis pulleys for spreading apart purposes and a set of vertical axis pulley pairs for clamping in position said conductor wires (30, 31 ). 6. A self-propelling automatic apparatus for overhanging contact lines according to claim 5, characterized in that at least two pulley pairs are provided for clamping in position said conductor wires (30, 31) and the pulleys of each pair can be alternatively opened in order to enable the lower clamp of the hanger to pass there through, after it is fastened to the respective conductor wire. 7. A self-propelling automatic apparatus for overhanging contact lines according to claim 1, characterized in that said upper spreading apart and grasping assembly (25) comprises a set of horizontal axis pulleys for spreading apart purposes and a set of vertical axis pulley pairs for clamping in position said messenger cable(s) (28, 29; 32). 8. A self-propelling automatic apparatus for overhanging contact lines according to claim 7, characterized in that at least two pulley pairs are provided to clamp in position said messenger cables (28, 29; 32) and the pulley of each pair can be alternatively opened in order to enable the hanger to pass there through after it is fastened to the respective messenger cable. 9. A self-propelling automatic apparatus for overhanging contact lines according to claim 7 and 8, characterized in that said upper spreading apart and clamping assemblies (25) are arranged upon oleodynamically operated vertically movable base structures (26) controlled in such a manner as to follow the catenary shaped profile of the messenger cables. 10. A self-propelling automatic apparatus for overhanging contact lines according to claim 1, characterized in that each of said magazines (16, 17, 18, 19) comprises two pulleys or toothed wheels around which a continuous belt or chain is extended and the hangers are removably suspended therefrom. 11. A self-propelling automatic apparatus for overhanging contact lines according to claim 10, characterized in that the hangers stored in said magazines have heights strictly corresponding to their installation positions along the catenary shaped messenger cables according to a pre-established hanger installation table and in addition the hangers are correspondingly successively arranged within the magazines so as to be successively picked up by said robots. 12. A self-propelling automatic apparatus for overhanging contact lines according to claim 1 , characterized in that an optical sensor is provided to locate the null or zero position of the line trunk along which the hangers have to be installed and to start the operation of the whole apparatus.

Inventors: DEL PRIORI MARIO, TALLO VALERIO, DEL PRIORI, MARIO, TALLO, VALERIO
Applicants: DEL PRIORI MARIO, SARTEM SPA, TALLO VALERIO, DEL PRIORI, MARIO, SARTEM S.P.A., TALLO, VALERIO
Application year: 1994
Main classification: B60M1
IPC codes: B60M1, B61D15